305 V8 with Rochester 4 barrel carburetor

I had the carburetor rebuilt and after the car warms up, when I let the car idle in neutral for a little bit the idle speed increases and won't go back down. If I shut the engine off and start it up again the idle speed is back where it needs to be until I let it idle again for a while and it goes up again.

Other things I've done, replaced all of the vacuum hoses, new plugs, wires, cap & rotor and set the timing.

Does any one have any suggestions on how to find the problem and fix it?

Thanks.

 

Here's what I found.

The fast idle for the cold start wasn't set correctly so the regular idle was set too high and once the car got to running temperature and was allowed to idle in neutral the rpm's would shoot way up.

So yesterday I set the running temp idle speed to 650 and shut it down for the day.

This morning I turned the screw in about a turn and started the car. Then I set the fast idle speed to about 1500.

When the car got up to running temperature and the choke finished opening up the idle came back down to 650. I let it idle in neutral for a while and everything was fine. So I took it for a ride and everything ran like it's supposed to.